Both critically ill and non-critically patients may present with altered mental status. This may include both delusions and hallucinations. When this occurs it is vital to distinguish between delirium and psychiatric causes, because the treatment and implications for the patient are very different.

Delirium results from an imbalance in certain neurotransmitters and is common in both ICU and non-ICU patients. It is also frequently missed or assigned a psychiatric etiology. This course presents the pathophysiology and implications of delirium along with an evidence based tool for rapid screening of the medically ill patient with delusions, delirium, or altered mental status.